Andre Ward went from having no answers to solving all the riddles of Sergey Kovalev's power Saturday night, wresting away the Russian's three light-heavyweight belts by a narrow decision settled by the final round.
Judges Burt Clements, John McKaie and Glenn Trowbridge rewarded Ward's impressive recovery from a second-round knockdown and gave him a unanimous-decision victory by three 114-113 scores before 13,310 at T-Mobile Arena.
"It was about those in-the-trenches moments," Ward said. "Sergey has no inside game, so I focused on mine, and that made the difference.
"He realized I wasn't going anywhere and I was stepping on the gas."
Kovalev, dealt his first defeat, quickly invoked a rematch clause against the still-unbeaten former super-middleweight champion from Oakland.
"It's the wrong decision. The witnesses are here; they saw it," Kovalev said. "I kept control. I lost maybe three rounds the whole fight. Here it is the USA and all the judges were from the USA. He is a boxer. Don't make it politics."
Ward (31-0) was trailing badly on the scorecards after getting backed up by an effective Kovalev jab in the first round, and having blood trickling from his right nostril in the second.
Then, Kovalev delivered a straight right to that nose, dropping Ward for only the second time in his career and leaving him reluctant to engage for most of the first half of the bout.
The fifth and eighth rounds were remarkably close as Kovalev noticeably reduced throwing the powerful right hand that had given him 26 knockout victories in his 31 previous fights.
That coincided with Ward's desperation to close the gap, and the boxer transformed to more of a fighter, especially in the seventh, when he repeatedly landed punches to the face and body.
"We landed the cleaner punches. Kovalev was aggressive, but not effective. That's why we won the fight," Ward's trainer Virgil Hunter said.
The punch statistics, like the scorecards, were narrowly decisive. Kovalev landed more punches (126-116) but at a worse percentage, and Ward out-jabbed him, 55-48.
Kovalev clearly wasn't intimidating Ward in the second half as he had in the first, and Ward steadily piled up the final rounds, winning the last six rounds on all judges' cards but one.
In the ninth, he cleanly struck Kovalev in the body, planted on some jabs and pounded Kovalev on the head with a punch that sent the Russian's head leaning outside the top rope.
The comeback enthused Ward, who peppered Kovalev with consecutive lefts in the 10th and seemed to tire the bigger man.
There was a fair amount of holding in the bout. Kovalev often put Ward in a headlock with his right arm. And Ward at times barreled into Kovalev, as if he had practiced tackling drills during training camp.
"I think Ward would be a great fighter in the UFC," Kovalev promoter Kathy Duva said. "The wrestling was outrageous. The ref [Robert Byrd] did nothing and I'm really upset."
Ward again answered Kovalev's pressure in the 11th, rocking his head back with a jab late in the round.
With the outcome on the line in the 12th, it was Ward's ability to land punches cleanly that won him the round in the minds of judges McKaie and Trowbridge, which broke the 104-104 tie on their scorecards.
Clements had given Ward the fifth through the 11th rounds after awarding Kovalev the first four rounds. Clements awarded Kovalev the 12th.
Earlier, Oxnard-trained light-heavyweight prospect Oleksandr Gvozdyk of Ukraine improved to 12-0 with his 10th knockout when former title challenger Isaac Chilemba failed to answer the bell for the ninth round. Chilemba was seen suffering in pain stemming from his right hand.
Gvozdyk, 29, is trained by super-featherweight world champion Vasyl Lomachenko's father.
Also, former middleweight title challenger Curtis Stevens (29-5) defeated James De La Rosa by unanimous decision, by scores of 98-90, 96-92, 96-92. Stevens is considered an outside contender to be Canelo Alvarez's next opponent.
Earlier, Claressa Shields' campaign to re-energize women's boxing began with a convincing, aggressive unanimous-decision victory over her former amateur foe Franchon Crews. Shields, the two-time U.S. Olympic gold medalist from Flint, Mich., won her pro debut, judges awarding her three 40-36 scores in a four-round super-middleweight bout.